The invention concerns a small cushion designed for anatomical support, especially to the lumbar and cervical regions, to be mounted onto the backs of seats.
Such small cushions are well known and are placed inside the seat backs of motor vehicles, their thickness and therefore projection being variable to suit the needs or preferences of the user.
These cushions are made by means of a device comprising a rigid structure combined with an elastic structure.
Convexity of the elastic structure in relation to the rigid structure may be obtained by a system of cams with a tie rod.
The cam is operated from outside the seat by means of a mechanism comprising a gear wheel and worm screw and a transmission shaft worked by an external knob.
The external structure consists of longitudinal metal bands crossing over transversal bands with outwardly projecting ends to ensure adequate spring.
This device is very complex and its outer surface is rough and sharp. It has therefore to be covered with a soft layer of considerable thickness.
The tie rod referred to above is involved in the curving movement of the elastic structure so that much effort is required to work the cam.
The worm strew is inserted to lessen effort when the device is adjusted but the knob has therefore to be given a great many turns making adjustment time far too long.
The device cannot be moved vertically from the lumbar to the cervical region or in between, or adapted to the stature, needs and preferences of the user.
These drawbacks lessen the advantages of the device not only due to its cost but also for practical reasons and duration.